From nobody Thu Oct 2 02:13:29 2025 Received: from fra-out-002.esa.eu-central-1.outbound.mail-perimeter.amazon.com (fra-out-002.esa.eu-central-1.outbound.mail-perimeter.amazon.com [3.65.3.180]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2DB7F30CD92; Mon, 29 Sep 2025 17:18:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=3.65.3.180 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759166313; cv=none; b=WWKfHs3V012UiaJ/75ywRUA/KOX/R06aL4eHLfpuBhtGh8I46rpd8X9WrPWGDNx0eau4llJTs2Dm+0VlwGRCLdGWWFSoIgLZJFm1ALiQ3Lq3R8B3FPavpCKw5E09XOgP4VNMPD+cjlUZgMoMpoGkIXd2ah5NHkfKqnBhV0Uu4Yk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759166313; c=relaxed/simple; bh=nlvxYaLaWRNdcmYPv9KL9mUJqKtD+ww79dSJfh94FPM=; h=From:To:CC:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=r5UkvYDimMkpgS/z3s92SgqcTMzRqw2FoLvnsHUrONPHgTT9mJYkYxpnGz/2kgnZLlUAOXwnCMaIigt5m9vsWwXgNfzz/y4JvpN9eoj3U247jLVrrR09hHzPX9Rms5MTvietXI3j30DRWFmMz6ZwwUzlScB4okKJ+KxNf2wjWUA= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amazon.com; spf=pass smtp.mailfrom=amazon.com; dkim=pass (2048-bit key) header.d=amazon.com header.i=@amazon.com header.b=pf24lI7k; arc=none smtp.client-ip=3.65.3.180 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amazon.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=amazon.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=amazon.com header.i=@amazon.com header.b="pf24lI7k" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazoncorp2; t=1759166311; x=1790702311; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=fgKTaT7jj0zRx6jbQ7DJOMsaZramokk9q66dhz8aLl4=; b=pf24lI7k+a3mSamuB5C+3/+v322OPaC9pPhvLCj3vgXxyMhOIEu1pZjR GUSmnaooRVW2y5YKgP6O+RyfL25Tr78H/w3FglTT/St+X5Wa+uDJbtrjj AZisKMHd8Nm+6DljQJFwZTTNGQyjBYCmlyJjWIuwxLEtq0PEypvzj44ev TMXVKJnG1Bd68C+Gl0LhYvbRLrC4LI4gaT3YhLD4yNrmLHq6pdh9ED6P1 J0O8QYnxgqxF8Yz1QHFhW35FMF4Tykdn9GGO8j/TCCPIv1OVquG1reRJR U/H5F6a7Jxy1cKSMIm/+KQEBtsEV4I9t5AGaODExb8G7B3HJboLgCAD50 Q==; X-CSE-ConnectionGUID: OdrA5m4GRTyucYO4c+QrvQ== X-CSE-MsgGUID: Zg99aBY4RPyloVBmDjPLpA== X-IronPort-AV: E=Sophos;i="6.18,302,1751241600"; d="scan'208";a="2846581" Received: from ip-10-6-6-97.eu-central-1.compute.internal (HELO smtpout.naws.eu-central-1.prod.farcaster.email.amazon.dev) ([10.6.6.97]) by internal-fra-out-002.esa.eu-central-1.outbound.mail-perimeter.amazon.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Sep 2025 17:18:21 +0000 Received: from EX19MTAEUB002.ant.amazon.com [54.240.197.232:9512] by smtpin.naws.eu-central-1.prod.farcaster.email.amazon.dev [10.0.22.27:2525] with esmtp (Farcaster) id 2b1e5247-c19f-44df-a0dc-a1c63bd8ce5f; Mon, 29 Sep 2025 17:18:20 +0000 (UTC) X-Farcaster-Flow-ID: 2b1e5247-c19f-44df-a0dc-a1c63bd8ce5f Received: from EX19D018EUA004.ant.amazon.com (10.252.50.85) by EX19MTAEUB002.ant.amazon.com (10.252.51.79) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.2562.20; Mon, 29 Sep 2025 17:18:18 +0000 Received: from dev-dsk-farbere-1a-46ecabed.eu-west-1.amazon.com (172.19.116.181) by EX19D018EUA004.ant.amazon.com (10.252.50.85) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.2562.20; Mon, 29 Sep 2025 17:18:15 +0000 From: Eliav Farber To: , , , , , , , , CC: Linus Torvalds , David Laight Subject: [PATCH v2 05/12 6.6.y] minmax: fix up min3() and max3() too Date: Mon, 29 Sep 2025 17:17:26 +0000 Message-ID: <20250929171733.20671-6-farbere@amazon.com> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20250929171733.20671-1-farbere@amazon.com> References: <20250929171733.20671-1-farbere@amazon.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-ClientProxiedBy: EX19D040UWA001.ant.amazon.com (10.13.139.22) To EX19D018EUA004.ant.amazon.com (10.252.50.85) Content-Type: text/plain; charset="utf-8" From: Linus Torvalds [ Upstream commit 21b136cc63d2a9ddd60d4699552b69c214b32964 ] David Laight pointed out that we should deal with the min3() and max3() mess too, which still does excessive expansion. And our current macros are actually rather broken. In particular, the macros did this: #define min3(x, y, z) min((typeof(x))min(x, y), z) #define max3(x, y, z) max((typeof(x))max(x, y), z) and that not only is a nested expansion of possibly very complex arguments with all that involves, the typing with that "typeof()" cast is completely wrong. For example, imagine what happens in max3() if 'x' happens to be a 'unsigned char', but 'y' and 'z' are 'unsigned long'. The types are compatible, and there's no warning - but the result is just random garbage. No, I don't think we've ever hit that issue in practice, but since we now have sane infrastructure for doing this right, let's just use it. It fixes any excessive expansion, and also avoids these kinds of broken type issues. Requested-by: David Laight Acked-by: Arnd Bergmann Signed-off-by: Linus Torvalds Signed-off-by: Eliav Farber --- include/linux/minmax.h | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/include/linux/minmax.h b/include/linux/minmax.h index 41da6f85a407..98008dd92153 100644 --- a/include/linux/minmax.h +++ b/include/linux/minmax.h @@ -152,13 +152,20 @@ #define umax(x, y) \ __careful_cmp(max, (x) + 0u + 0ul + 0ull, (y) + 0u + 0ul + 0ull) =20 +#define __careful_op3(op, x, y, z, ux, uy, uz) ({ \ + __auto_type ux =3D (x); __auto_type uy =3D (y);__auto_type uz =3D (z);\ + BUILD_BUG_ON_MSG(!__types_ok3(x,y,z,ux,uy,uz), \ + #op"3("#x", "#y", "#z") signedness error"); \ + __cmp(op, ux, __cmp(op, uy, uz)); }) + /** * min3 - return minimum of three values * @x: first value * @y: second value * @z: third value */ -#define min3(x, y, z) min((typeof(x))min(x, y), z) +#define min3(x, y, z) \ + __careful_op3(min, x, y, z, __UNIQUE_ID(x_), __UNIQUE_ID(y_), __UNIQUE_ID= (z_)) =20 /** * max3 - return maximum of three values @@ -166,7 +173,8 @@ * @y: second value * @z: third value */ -#define max3(x, y, z) max((typeof(x))max(x, y), z) +#define max3(x, y, z) \ + __careful_op3(max, x, y, z, __UNIQUE_ID(x_), __UNIQUE_ID(y_), __UNIQUE_ID= (z_)) =20 /** * min_not_zero - return the minimum that is _not_ zero, unless both are z= ero --=20 2.47.3